Smithfield Foods Inc. closed its Tar Heel, North Carolina, pork packing plant, the world's largest, on Tuesday after a water tank collasped and caused an ammonia leak, the company said.
It did not say when the plant would resume operations, noting only that Tueday's shifts were canceled.
At least three people were injured and transported to Cape Fear Hospital in Fayetteville, North Carolina, a Bladen County firefighter told Reuters by telephone.
"Earlier today, a large water tank collapsed at our Tar Heel facility, disrupting power systems and causing an ammonia release. The release was minor and is now contained," Kathleen Kirkham, a company spokeswoman, said in a statement.
Several rural fire departments responded to the incident, the Bladen County firefighter said.
The company said later emergency crews had left the facility and company officials were evaluating the site.
All employees at the packing plant were evacuated and sent home, but roads around the plant have been reopened.
The plant has a daily slaughter capacity of about 34,000 hogs. Smithfield Foods, Inc., the world's largest pork producer and processor, is a wholly independent subsidiary of China's WH Group.
Word of the plant evacuation had little or no effect on Chicago Mercantile Exchange hog futures, according to traders.
CME hog futures for June delivery ended up 0.675 cent per lb to 124.925 cents. August ended down 0.225 cent per lb to 128.050 cents. (Reporting by Meredith Davis; Additional reporting by Theopolis Waters; Editing by Dan Grebler)